The Claim: A television ad by opponents of same-sex marriage claims that if Referendum 74 is approved, “same-sex marriage could be taught” in Washington schools.

The spot features parents in Massachusetts who say their son’s school taught that boys could marry boys, in contradiction to the family’s religious beliefs. After they and another family sued, they say, the courts ruled the parents had no right to take children out of their classes or be informed when such lessons were going to take place.

We find: Half true.

Campaign ads about the impact of same-sex marriage on children have proved effective for opponents of gay marriage in states where they’ve been used — primarily in California, where the 2008 passage of Proposition 8 banned gay marriage.

The ads, which are also airing in the three other states with same-sex-marriage measures on the ballot, are meant to conjure up the most negative images of what schools might teach children if same-sex marriage is legalized.

In reality, in classrooms across the state and the country, teachers are already having conversations with children about different kinds of families — those of mixed race or religion, or those headed by single parents, grandparents, two moms or two dads.

And lessons about families are already part of the grade-level requirements for first-graders in Washington schools — the idea being that it helps prepare them to function as citizens in a diverse society.

But those requirements say nothing about any kind of marriage, and schools typically don’t raise the subject — in deference to students who come from homes where the adults may not be married.

Perhaps more importantly, there’s no direct link between school curricula and same-sex-marriage laws — not the ones that exist in six states and the District of Columbia or the law that Washington voters are being asked to approve or reject Tuesday. Supporters of gay marriage consider the potential impact of these ads so powerful that their campaign immediately launched a counter ad. While that ad, by Washington United for Marriage, doesn’t directly address the other side’s claim, it features an Edmonds couple saying children learn their most important values at home, from their parents.

In a statement, Randy Dorn, state superintendent of public instruction, called the claim in the ad by same-sex-marriage foes a red herring, saying that modifying curricula is a long, detailed process that involves school boards, administrations, teachers and parents.

“Parents should be reassured that nothing will change under R-74 when it comes to our public schools,” he said.

The ad by Preserve Marriage Washington begins with an image of parents David and Tonia Parker of Massachusetts, which became the first state in the nation, eight years ago, to allow gays to marry.

The 30-second spot shows the Parkers leafing through a book as a voice explains that if gay marriage happens here, (in Washington), schools could teach that boys can marry boys.

It then cuts to David Parker, who says that is what happened at his son’s school after marriage was legalized in Massachusetts. He was referring to the case of a schoolmate of his son’s whose second-grade teacher read the class a book, “King and King,” in which two princes married.

Tonia Parker next says that “If Referendum 74 is approved, same-sex marriage could be taught in local Washington schools just as it was in Massachusetts.”

What the ad doesn’t say is that the Parkers’ son was not in the class where the book was read, but in 2005, he took home a book entitled, “Who’s in a Family?” That book, which was not required reading, concludes by answering its own question: “The people who love you the most.”

In a lawsuit filed in federal court, the Parkers and the family of their son’s schoolmate said they weren’t challenging the district’s use of these books but rather its refusal to provide them prior notice and allow them to opt out.

While Massachusetts schools do allow children to be exempt from lessons that primarily involve human sexuality, school officials had denied the families the opportunity to opt out because they said the lessons were not of a sexual nature.

The courts sided with the school.

In Washington, the Office of the Superintendent of Public Instruction has grade-level expectations, called GLEs, for what children are required to know. For first-graders, they require social-studies lessons on families, which is where most conversations regarding family structure and diversity arise.

Such conversations also may occur when kids are bullied for any number of reasons, including because their parents are gay.

What form these discussions take can differ from district to district, school to school and maybe even classroom to classroom.

It’s hard to know what might happen in schools if same-sex marriage is legalized in Washington.

In its ruling in the Massachusetts case, the 1st U.S. Circuit Court of Appeals pointed out that since Massachusetts legally recognized gay marriage, it was rational for its schools to educate students regarding that recognition.

We find the ad’s claim half true because, while it does not directly state that schools here would be required to teach about same-sex marriage, viewers are left with that impression.